Overlapping Barrel Cam Errors

[twdrummer]

Hey guys, new to the forum here so forgive me for any nube mistakes. Anyway, I've been trying for a couple days now to model a barrel cam slot into a shaft which overlaps itself and returns back to its origin. I'm not sure of the best way to describe this but it's not just a simple cam slot which moves a cam a short distance, dwells, then moves the cam back, I actually need to move an outer roller(riding on this shaft) a long distance(several revolutions), then turn around and come back. The term for this motion I would describe as an oscillating motion. I've drawn my cam track on a plane tangent to my outer diameter, and wrapped to my desired depth. The weird part is, If I only draw half of my profile it will wrap fine, but when I try the entire path which reverses the direction of the slot, I keep getting intersecting errors. I tried only wrapping half of the profile and mirroring the feature also but again had no luck. Can anybody tell me what the heck I'm doing wrong here? Thanks in advance...Trent

 

[Updraft]

It sounds like you are trying to make the cam for a level-wind mechanism. You might try making a helical sweep instead of wrapping the profile. However you approach it you won't be able to do it in one feature since by definition the cut overlaps itself. I suggest making the cut for the forward traverse and then making a separate cut for the retract. Since one is left hand and the other is right hand you won't be able to mirror the first cut to make the second. If there is some dwell at the ends then the guide curve for the sweep will be a compound curve consisting of the helical main portion plus some end pieces.

I haven't looked, but I wouldn't be surprised if you could find a good example of this type of part in 3D ContentCentral.

Be aware that sweeping a profile is not the same as sweeping a solid so you'll need to check your groove for how well the follower fits. I'm not on SWX2016 yet, but I seem to recall in the 2016 rollout session something about the new version having a capability to sweep a solid so you might look into that.

- - -Updraft

 

[twdrummer]

Updraft, thank you for the reply. You are correct by assuming a level-wind cam is what I'm trying to make but I'm using it in a different application. I wasn't even aware of the terminology for the mechanism so thank you for bringing that to light. Actually, I think I've achieved what I was hoping to do by simply wrapping half of the profile using arcs at the "turn-arounds" and a straight line for the helical portion. I used global variables to control the height and length of my "straight line"(helix), height being pitch*revs and length being (Pi*D)*revs. Then I mirrored the feature about my front plane, which I had made coincident to the starting point of my profile. It looks great for the part I'm doing now but when I change my global variables to attain a different cam profile, in some cases my mirror feature will error. I don't really understand why it's happening intermittently like it is but I'll cross that bridge when I get there I guess. Thanks again for the help!